Salivary gland diseases

3 major salivary glands: parotid, submandibular, sublingual (+ many minor salivary glands)

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A) Sialadenitis (Inflammation of Salivary Glands)

Traumatic — Mucocele (most common inflammatory lesion)

• Trauma → blocks and ruptures salivary gland duct → leakage of saliva into surrounding tissues
• Histology: cyst-like space lined by inflamed granulation tissue filled with saliva
• Usually appears as a swelling of the lower lip
• Treatment: excision of cyst + salivary gland lobule

Viral — Mumps (most common viral form)

• Caused by paramyxovirus
• Enlargement of major salivary glands, mostly the parotid glands
• Children: self-limited; adults: may be accompanied by pancreatitis or orchitis

Bacterial

• Most often secondary to ductal obstruction from stone formation (sialolithiasis)
• Usually due to S. aureus or S. viridans
• May cause: low salivary flow, xerostomia (dry mouth), or abscess formation

Autoimmune — Sjögren Syndrome

• Autoimmune-inflammatory destruction of lacrimal and major/minor salivary glands → auto-antibodies against the gland
• Causes: dry mouth (xerostomia) + dry eyes (keratoconjunctivitis sicca)
• Primary = sicca syndrome
• Secondary = in association with RA, SLE, or scleroderma

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B) Salivary Gland Tumors

• 80% of tumors occur in the parotid glands (mostly benign)
• Submandibular gland: half benign
• Sublingual and oral mucosal glands: mostly malignant
• Key rule: likelihood of malignancy is inversely related to the size of the gland

Benign Tumors

1. Pleomorphic Adenoma (mixed tumor) — most common benign tumor

• Usually in the parotid gland; slow-growing, encapsulated, well demarcated
• Causes painless swelling at the angle of the jaw
• Despite encapsulation, often penetrates the capsule → adequate parotid resection required to prevent recurrence (facial nerve often impaired during surgery)
• Composed of ductal (epithelial) and myoepithelial cells

2. Warthin Tumor (papillary cystadenoma lymphomatosum)

• Occurs only in the parotid gland; more common in males
• Macro: small, well-encapsulated cystic spaces containing mucin
• Micro: cystic spaces lined by tubular epithelium embedded in lymphoid stroma

Malignant Tumors

1. Mucoepidermoid Carcinoma — most common salivary gland malignancy in adults

• Mainly in the parotid glands
• Composed of a mix of squamous cells + mucus-secreting cells + intermediate cells
• Slow-growing (up to 8 cm); no capsule; often infiltrative

2. Adenoid Cystic Carcinoma — 2nd most common malignant salivary tumor

• Occurs in minor salivary glands of the palate
• High tendency to infiltrate perineural spaces → pain
• Tumor cells form cribriform structures (adenoid), filled with excess basement membrane material
• Slow-growing malignancy with late metastasis

💡 High-yield: Malignancy risk inversely proportional to gland size. Pleomorphic adenoma = most common benign; penetrates capsule; parotid; facial nerve at risk. Warthin = parotid only; males; lymphoid stroma. Mucoepidermoid = most common malignant; parotid. Adenoid cystic = minor glands; perineural invasion; cribriform. Mumps = paramyxovirus; orchitis in adults. Sjögren = dry eyes + dry mouth; anti-salivary gland antibodies.